In the installation and use of a gas fireplace insert, a flue liner must be provided to conduct the flue gases from the firebox of the fireplace insert to the chimney of the fireplace. As well, with direct vent fireplace inserts, fresh air from the outside is fed to the firebox for combustion. A second flue liner is needed to carry this fresh air down the chimney to the firebox where combustion occurs.
Typically, the flue liner for the exhaust gases is connected to the outlet opening on the firebox and pushed upwards into the fireplace chimney to ensure that the exhaust gases are directed entirely up the chimney so that no exhaust gases can leak into the space between the firebox and the fireplace, thereby escaping into the room. As well, the flue liner for the inlet fresh air should be inserted well into the chimney and apart from the exhaust gas flue liner to ensure that only fresh air is fed to the firebox, and not exhaust gases.
In the past, it has been problematic to install flue liners to gas fireplace inserts because of the extremely restricted amount of space between the fireplace insert and the walls of the fireplace cavity when the fireplace insert is inserted into the fireplace. Therefore, it is often very difficult to maneuver the flue liners up the chimney or to connect the flue liners properly to the firebox to ensure a tight and leak-proof connection.
With a direct vent gas fireplace insert, it is necessary, in order to achieve high efficiency, that there is a tight, leak-proof connection of the flue liners to the fireplace insert, thereby creating a continuous circuit of flowing gases. That is, there should not be any leaks of gases between the inlet of the fresh air flue liner and the outlet of the exhaust gas flue liner so that there are no exhaust gases that leak into the room nor any room air sucked into the firebox and combusted. This substantial leak-proof continuous circuit of flowing gases must be maintained, particularly at the points or the two flue liners connect to the gas fireplace insert.
In Canadian Patent No. 1,281,249 issued on Mar. 12, 1991 and currently standing in the name of the Applicant herein, a method and adaptor for installing a flue liner to a fireplace insert is disclosed. In that case, the fireplace insert is not a direct vent fireplace insert, thus it is not necessary to keep a strict leak-proof circuit of flowing gases. In fact, because it is not a direct vent fireplace, the insert does not have a fresh air inlet to the firebox, thereby not necessitating a second flue liner. As such, a leak-proof circuit between the fresh air inlet and the exhaust air outlet is not required. The fireplace insert in that case uses room air for combustion instead of fresh outside air.
In U.S. Pat. No. 1,281,249, the adaptor is described as a sliding flue liner adaptor on which the lower end of the flue liner is connected. The adaptor then engageably slides in brackets located on top of the fireplace insert when the insert is placed in the fireplace cavity. An opening is located in the adaptor where the flue liner connects thereto, and the opening is disposed such that it corresponds with the exhaust opening in the firebox when the adaptor is slid fully into the brackets. The adaptor may then be secured to the fireplace insert. The result is the simple connection and installation of the exhaust flue liner to the fireplace insert.
There is a need, therefore, for an adaptor to be used to install direct vent gas fireplace inserts, and to make the connection of the flue liners to the insert easier.